There is a technology known in the related art, whereby image data expressed in a color space assuming nonlinearity to intensity signals corresponding to the three primary colors of light are first converted to image data expressed in a color space achieving linearity to the individual intensity signals corresponding to the three primary colors of light, the image data expressed in the linear color space undergo color conversion processing through matrix conversion and the image data having undergone the color conversion processing are converted back into image data expressed in the non-linear color space (see, for instance, patent reference 1).    Patent reference 1: Japanese Laid Open Patent Publication No. 2002-116750